The present invention is directed to a catalyst for promoting the synthesis of alcohols from olefin by the so-called hydroformylating reaction.
Hydroformylating has been understood to be a reaction in which aldehydes were formed from olefins and synthesis gas (H.sub.2 +CO). The thus-obtained aldehydes were frequently hydrated to become alcohols: ##STR1## This process was invented by O. Roelen in Germany in 1938.
The starting materials may be either pure olefin or a mixture of olefins. Those olefins which react most rapidly have a double bond at the end of the carbon chain (.alpha.-olefins). Other olefins having a straight chain react less rapidly, while the slowest reactants are the olefins having a branched chain. By controlling the composition of the starting mixture, it is possible to influence the isomer distribution of the product mixture.
Homogeneous catalysts have been employed in the industrial processes. The process conditions are strongly dependent on the catalyst. Typical catalysts have been cobalt hydrocarbonyl HCo(CO).sub.4, cobalt carbonyl modified with trialklyphosphine, e.g., (Co(CO).sub.3 P(C.sub.4 H.sub.9).sub.3).sub.2, and rhodium carbonyl modified with triphenylphosphine, HRh(CO)(PPh.sub.3).sub.3.
Homogeneous hydroformylation has conventionally included six steps:
(1) hydroformylation, PA0 (2) removal of the catalyst from the reaction mixture, PA0 (3) regeneration of the catalyst, PA0 (4) purification of the aldehyde, PA0 (5) hydration, and PA0 (6) distillation of the alcohol. PA0 (1) hydroformylation, PA0 (2) distillation of the alcohol.
If the process can be accomplished with the aid of a solid catalyst without the aldehyde intermediate step, then the number of processing steps can be reduced to two:
This considerably simplifies the hydroformylation process.
U.S. Pat. No. 4,144,191 discloses a bimetallic cluster catalyst for single-step production of alcohols by hydroformylation. The cluster compound is the rhodium-cobalt cluster Rh.sub.x Co.sub.y CO.sub.12, where x and y are integers between 1 and 3, and .SIGMA.(x+y)=4. The compound may be prepared, for instance, according to the following reaction equation: EQU 3Co.sub.2 (CO).sub.8 +2Rh.sub.2 (CO).sub.4 Cl.sub.2 .fwdarw.2Co.sub.2 Rh.sub.2 (CO).sub.12 +2CoCl.sub.2 +8CO
The resulting bimetal cluster is highly air-sensitive, and therefore requires very precise handling. As taught by this patent, when the monometal clusters Rh.sub.4 (CO).sub.12 and Co.sub.4 (CO).sub.12 were separately used, the forming of alcohols decreased substantially. The mixture of monometal clusters Rh.sub.4 (CO).sub.14 and Co.sub.2 (CO).sub.8 produced aldehydes to a large degree.